TWI552525B - Switching topology for connecting two nodes in electronic system - Google Patents

Description

Switch the topology used to connect two nodes in an electronic system

The present invention relates to electronic systems, and more particularly to switching circuits for providing connections between two nodes with different voltages.

The circuit for providing between two nodes with different voltages includes a regulator, a heat exchange circuit and a surge suppression circuit. The regulator converts the power between the nodes in a controlled manner. When the starting voltage is different, the heat exchange circuit will The two nodes are connected together, and the surge suppression circuit protects one node from voltage surges on other nodes. The two nodes usually have a large capacitance in any real circuit, and if the nodes are suddenly connected together, they can generate a large current to flow quickly. Care needs to be taken to ensure that transient voltage interference does not occur on both nodes when the two nodes are connected.

Dissipative components are often used in circuits that provide connections between nodes. This typically requires large switching devices and advanced controllers, and advanced controllers adjust the time and slew rate to keep the switching power dissipated within security limits. This method maintains continuous current conduction at the input node and the output node during the connection event while minimizing the voltage at each node and device that can be connected to the nodes. interference. However, during the connection interval, high power is likely to be dissipated across the switching device. The temperature of the switching device (such as a power transistor that can include a heat sink) is thus greatly increased during the connection event. This switching device must be sized to cope with temperature rises. At higher power levels, finding a transistor device that can operate reliably can be quite difficult.

Alternatively, the connection circuit can use a conventional buck regulator to exchange the topology to limit current flow to the safety level by adjusting the duty cycle of the exchange. This reduces the power loss during the connection interval but causes the current at the input node to be discontinuous, possibly interrupting or damaging the connector and circuit coupled to the node.

Therefore, there is a need for new connectivity topologies that minimize power dissipation and provide continuous current conduction.

According to one aspect, the present invention provides a circuit for connecting between a first node of a first voltage and a second node of a second voltage. The circuit has a first inductive component, a first inductive component, a second inductive component, and a second inverting component, wherein the first inductive component has a first terminal coupled to the first node, and the first switching component is coupled to the first inductor Between the second terminal of the component and the second node, the second inductive component has a first terminal and a second terminal, the first terminal configured to receive current from the second terminal of the first inductive component, the second terminal and the second terminal The third node is coupled between the first terminal and the second node of the second inductive component. The third node can be grounded. The first switching element is configured to provide a first path for current flow between the first node and the second node when the first switching element is open and the second switching element is off. When the second switching element is turned on and the first switching element is turned off, the second switching element is configured to provide A second path for current flow between the first node and the second node.

Furthermore, the capacitive element can be coupled between the second terminal of the first inductive component and the first terminal of the second inductive component.

The circuit can further include a controller configured to control a duty cycle of the first switching element or a duty cycle of the two switching elements.

For example, one of the switching elements can be a transistor, while the other switching elements can be diodes, and when the first switching element is turned off, the diodes are configured to conduct current. Alternatively, both switching elements can be a transistor.

In one embodiment, the first inductive component and the second inductive component are magnetically disengageable. In another embodiment, the first inductive component and the second inductive component are magnetically coupled. The first inductive element and the second inductive element may be of the same value or may have different values.

The circuit can further include a current sense resistor configured to determine a sum of current flow through the first inductive element and the second inductive element.

In accordance with an aspect of the present disclosure, a controller can be configured to control a switch of a first switching element to provide a voltage of a second node, the voltage of the second node being adjusted relative to a voltage of the first node. For example, the voltage of the second node can be provided to a desired extent, and the required voltage of the second node is less than the voltage of the first node.

In one embodiment, the circuit can be configured as a voltage mode switching regulator with a feedback loop to provide a value representative of the voltage of the second node to the controller.

In another embodiment, the circuit can be configured to have feedback back The current mode of the loop switches the regulator to provide a value indicative of the voltage at the second node to the controller, and a current sense resistor that enables the controller to determine the current at the second node.

In a further embodiment, the controller can be configured to operate in a fixed frequency mode.

In another embodiment, the controller can be configured to operate in hysteresis mode.

Further, the circuit can be configured to act as a heat exchange circuit to attach a load to the second node to receive a voltage from the first node.

Furthermore, the circuit can be configured as an overvoltage protection circuit to protect the load coupled to the second node from voltage spikes at the first node.

According to the method disclosed by the present invention, the following steps may be performed to provide a connection between a first node of a first voltage and a second node of a second voltage: - a first inductive component between the first node and the third node The capacitive element and the second inductive element are coupled in series, wherein the third node is grounded, and the first switching element is coupled between the second node and a node, the node is connected to the first inductive element and the capacitive element, Coupling a second switching element between the second node and a node, the node connecting the second inductive element and the capacitive element, and - switching the first switching element and the second switching element to provide the first switching element and the second The first current flow of the switching element is exchanged with the second current flow.

The second switching element can be turned off when the first switching element is turned on, and the second switching element can be turned on when the first switching element is turned off.

The invention will be readily apparent from the following detailed description, which is set forth in the <Desc/Clms Page number> The disclosed embodiments of the present invention are described. As will be described, the invention may be applied to other and different embodiments, and the details are susceptible to variations in various aspects. Accordingly, the illustrations and description are to be regarded as illustrative rather than limiting.

10‧‧‧Switch circuit

12‧‧‧ Controller

20‧‧‧Switch Regulator

22‧‧‧ Controller

30‧‧‧Switch Regulator

32‧‧‧ Controller

40‧‧‧Switch Regulator

42‧‧‧ Controller

44‧‧‧Amplifier

46‧‧‧ comparator

48‧‧‧Latch

50‧‧‧Switch circuit

52‧‧‧ Controller

54‧‧‧Amplifier

56‧‧‧ comparator

60‧‧‧Heat exchange circuit

62‧‧‧ Controller

70‧‧‧Overvoltage protection circuit

72‧‧‧ Controller

L1‧‧‧Inductance components

L2‧‧‧Inductive components

C1‧‧‧Capacitive components

Cout‧‧‧ output capacitor

T1‧‧ ‧ time interval

T2‧‧ ‧ time interval

S1‧‧‧ switching components

S2‧‧‧ switching components

R1‧‧‧Resistors

R2‧‧‧ resistor

R3‧‧‧Resistors

M1‧‧‧ MOSFET

M2‧‧‧ MOSFET

D1‧‧‧ diode

Iref‧‧‧reference current value

The following detailed description of the embodiments of the present invention can be construed as a 1A-1C shows an exemplary exchange topology for connecting two nodes according to the present invention, FIG. 2 shows an exemplary embodiment of the topology in FIG. 1, and FIG. 3A-3E shows a second diagram. Time chart of current in the circuit, FIG. 4 illustrates an exemplary voltage mode switching regulator with the topology disclosed by the present invention, and FIG. 5 illustrates an exemplary current mode switching regulator with the topology disclosed by the present invention FIG. 6 illustrates an exemplary fixed frequency mode switching regulator with the topology disclosed by the present invention, and FIG. 7 illustrates an exemplary hysteresis mode switching regulator with the topology disclosed by the present invention. Fig. 8 is a diagram showing an exemplary heat exchange circuit with the topology disclosed in the present invention, and Fig. 9 is a view showing an exemplary overvoltage protection circuit with the topology disclosed in the present invention.

The present disclosure is made using a specific example of an exchange topology for connecting two nodes with different voltages. However, various other variations of the circuit for connecting the present invention will be apparent to those of ordinary skill in the art.

FIG. 1A illustrates a switching circuit 10 for providing a connection between an input node "input" and an output node "output" in an electronic system. The output voltage of the output node can be different from the input voltage applied to the input node. The circuit 10 includes an inductance element L1, a capacitance element C1 and an inductance element L2 connected in series between the input node and the voltage supply node to provide a voltage less than the output voltage level. As shown in Figure 1A, the voltage supply node can be a ground node.

The main path switching element S1 is coupled between the output node and a node, and the node connects the inductive element L1 and the capacitive element C1. The auxiliary path switching element S2 is coupled between the output node and a node, and the node connects the inductive element L2 and the capacitive element C1.

1B and 1C show control signals 1 with 2 is provided to control the time chart of the switching elements S1 and S2, respectively. During time interval T1, switching element S1 is turned on, providing a primary path for current flow between the input node and the output node. During time interval T2, switching element S2 is turned on, providing an auxiliary path for current flow between the input node and the output node. When the switching element S1 is turned on, the switching element S2 is turned off, and when the switching element S2 is turned on, the switching element S1 is turned off.

The inductive elements L1 and L2 can be independent, that is, magnetically disengaged. Alternatively, the inductive elements L1 and L2 may share a single core, that is, they may be magnetically coupled. As long as the capacitive element C1 is connected to L1 and L2, continuous power conduction is provided between the input and output nodes. If the inductive elements L1 and L2 are magnetically coupled, the inductive element C1 can be selectively removed from the circuit 10. However, in this case, the current between the input and output nodes is not continuous.

An exemplary embodiment of the switching circuit 10 is shown in FIG. For example, MOSFET M1 can be used as switch S1, and diode D1 can be used as switch S2. Switches S1 and S2 can be implemented by MOSFETs, IGBTs or bipolar transistors, or by diodes. A current sense resistor R1 can be provided between the output node and the switches to monitor the output current. Controller 12 can determine the current flow through resistor R1 to control the switching of MOSFET M1.

3A-3E illustrate currents flowing through the MOSFET M1, the diode D1, the sense resistor R1, the inductor element L1, and the inductor element L2, respectively. During time interval T1 determined by controller 12, MOSFET M1 is turned on by controller 12 and the predetermined peak current threshold set by controller 12 is reached by the current buildup of M1.

During time interval T2, controller 12 turns off M1 and current flows through the alternate current path provided by diode D1. When the time interval T2 of the controller is exceeded or the current induced by the sense resistor R1 decreases by a predetermined threshold, the controller turns M1 on. The switch of M1 is repeated until controller 12 determines that the input and output voltages are equal. The currents at the input, output, and ground nodes are all continuous The mode flows and the sum of the currents through L1 and L2 is equal to the output current flowing in R1.

During the time interval T1, the voltage difference between the input and output nodes occurs across the inductive element L1. When the switch M1 is turned on, the remaining energy is absorbed by the reaction elements L1, C1 and L2. During the next time interval T2, the reactive elements L1, C1 and L2 return the stored energy to the output node and maintain a continuous input current flow. When the continuous current conduction of the input and output nodes is maintained at the same time, the controller 12 exchanges current flow primarily with the auxiliary current path.

As discussed in more detail below, circuit 10 can use current or voltage mode feedback to provide switching regulation between the input and output nodes. Controller 12 can use various exchange control modes, including hysteresis mode, fixed frequency mode, constant on/off time, or any other scheme for controlling switches S1 and S2 to equalize the input and output voltages.

For example, Figure 4 illustrates an exemplary switching regulator 20 with voltage mode feedback. A voltage divider consisting of resistors R2 and R3 is coupled to the output node to determine the output voltage of the node between R2 and R3. The output capacitor Cout is also coupled to the output node. The controller 22 can control the switching of the MOSFET M1 based on the output voltage to exchange current flow between the primary and auxiliary paths until the output voltage is equal to a predetermined value.

Figure 5 illustrates an exemplary switching regulator 30 with current mode feedback. The controller 32 can control the switching of the MOSFET M1 based on the output current induced by the sense resistor R1 to exchange current flow between the primary and auxiliary paths until the output voltage of the node between R2 and R3 is equal to a predetermined value.

Figure 6 shows the controller 42 with operation in a fixed frequency mode An exemplary exchange regulator 40 is shown. Controller 42 includes an operational amplifier 44 to monitor the voltage drop across sense resistor R1. This voltage drop represents current flowing through resistor R1. Comparator 46 compares the output signal of operational amplifier 44 with a signal representative of reference current value Iref. The RS latch 48 has a set input S with a fixed frequency clock signal and a reset input R with a comparator output signal. The fixed frequency clock signal can be generated by the oscillator. Switch M1 is controlled by the output signal of RS latch 48.

When the latch 48 is set at the beginning of each clock cycle of the clock signal, the output of the RS latch 48 goes high to open the switch M1 and provide current flow through the main current path. When the current induced by resistor R1 is reduced to the Iref value, the output of latch 48 goes low, turning off switch M1 and providing current flow through the auxiliary current path provided by diode D1. The M1 switch continues until the output voltage is at the desired level.

Figure 7 illustrates an exemplary switching regulator 50 with a controller 52 operating in hysteresis mode. Controller 52 includes an operational amplifier 54 to monitor the voltage drop across sense resistor R1, which represents current flow through resistor R1. The hysteresis comparator 56 compares the output signal of the operational amplifier 54 with a signal representative of the reference current value Iref to produce an output signal that controls the switch of the switch M1.

Figure 8 illustrates an exemplary embodiment of a heat exchange circuit 60 having an exchange topology as disclosed herein. The heat exchange circuit controls the increase in the load voltage when the load is supplied with the input voltage. Even if the input voltage suddenly changes, for example, when the circuit is suddenly connected to the field power supply, the voltage and current changes are kept under control. Conventional heat exchange circuits have large MOSFET transistors that operate with linear regulators that have a controlled increase in output voltage the same. The dv/dt is controlled as such, but the transistor spends a lot of time for the current to carry the voltage drop across the drain to the source, which dissipates the power and causes thermal stress on the MOSFET. This stress requires the selection of a suitable MOSFET with a suitable heat sink.

Figure 8 illustrates that the switched topology of Figure 1 is configured as a heat exchange circuit 60. The input voltage is applied to the input node and the load is attached to the output node. The heat exchange circuit 60 includes a controller 62 that adjusts the duty cycle of the MOSFET M1 as the output voltage rises, and the controller 62 acts as a function of time.

Before the start of a typical heat exchange event, M1 is turned off, the voltage at the output node is zero, and no current flows in the inductive element L1 or L2. M1 is initially turned on by controller 62 during a low duty cycle. When M1 is turned on, current flows through the inductive element L1 and flows from the transistor M1 to the sense resistor R1, and then to the load of the output capacitor Cout and the output contact. Due to the inductance of L1, the current rises from the zero slash to the value controlled by L1, the input voltage, and the M1 turn-on time.

When the transistor M1 is turned off, the current suddenly stops flowing in M1 and the remaining energy stored in the inductance element L1 causes the voltage at the drain of M1 to rise rapidly. The capacitive element C1 causes the positive pole of the diode D1 to also rise, and when the positive voltage of D1 exceeds the negative voltage of the diode D1 (which is approximately equal to the voltage of the output node), the diode D1 will begin to conduct current. This current will flow through L1 and C1, then through D1 to the sense resistor R1 and the load. If L1 and L2 are coupled to an inductor with the phase shown in Figure 8, the portion of the current in L1 will transition into the current of L2 and will flow from L2 to D1 and again to R1 and the load.

If L1 and L2 are independent inductors, several parts of L1 current The points will flow to L2 instead of the initial stream to D1. After several cycles have occurred, this will cause the voltage on the capacitive element C1 to increase, and the polarity of the current in L2 to reverse and behave as a condition that the image is coupled to the inductor.

As the duty cycle of M1 increases, the current in L1 increases and the voltage at the output node increases in a controlled manner. When the duty cycle of M1 is close to 100% (ie, transistor M1 is continuously open), the voltage of the output node will be close to the voltage of the input node, and the current in L1 will be close to the load current, that is, the heat exchange cycle is completed.

The heat exchange circuit 60 disclosed in the present invention has an advantage over a conventional linear heat exchange circuit in which the MOSFET M1 operates only as a switch and does not observe the voltage from the drain to the source while carrying current. This means that a MOSFET with a low on-resistance RDS(on), including those with a limited safe operating area (SOA), can be used as the transistor M1. It also minimizes power dissipation in M1 while minimizing the need for a diffuser.

Other advantages of the heat exchange circuit 60 are that the currents at the input and output nodes are smooth and continuous in a manner similar to linear heat exchange circuits, minimizing the need for input or output filters.

Figure 9 illustrates an exemplary overvoltage protection circuit 70 based on the switched topology of Figure 1. The overvoltage protection circuit 70 is configured to protect the load coupled to the output node from voltage peaks at the output node. The overvoltage protection circuit 70 includes the controller 70 and operates in the same manner as the heat exchange circuit 60 of FIG. However, the overvoltage protection circuit 70 also includes a resistor divider comprised of resistors R2 and R3 to measure the voltage at the output node, and a feedback loop to supply the measured output voltage to the controller 72. Furthermore, the circuit 70 includes MOSFET M2, not diode D1.

When a predetermined level of output voltage is reached, the duty cycle of transistor M1 is controlled by controller 72 to a value less than 100%. This duty cycle control causes the overvoltage protection circuit 70 to act as a buck voltage regulator, wherein the output node remains at a constant voltage even when the voltage at the input node rises above the voltage of the output node. This behavior allows the overvoltage protection circuit 70 to operate as a buck voltage regulator, and if the preset output voltage is set lower than the expected input voltage, the overvoltage protection circuit 70 can reduce the input voltage to the desired output level.

Alternatively, if the preset output voltage is set to an input voltage that is higher than the normal steady state, but less than the peak voltage expected by the input node (ie, the input voltage peak), the overvoltage protection circuit 70 can operate as a surge suppressor. When the overvoltage protection circuit 70 operates as a surge suppressor and the glitch reaches the input node, during the glitch, the controller 72 will adjust the duty cycle of the transistor M1 from 100% of the steady state operation to a lower duty cycle. To keep the output voltage at a preset value or lower than the preset value. Further, when the transistor M1 is turned off, the controller 72 controls the transistor M2 to turn the transistor on, and when M1 is turned on, it turns off M2.

The foregoing description illustrates and describes aspects of the invention. Furthermore, the present invention discloses an embodiment that only shows and describes preferences, but as described above, it can be appreciated that the present invention can be applied to other combinations, variations, and environments, and can be within the scope of the inventive concepts described herein. Changes or modifications may be made to the knowledge of the above-mentioned teachings and/or related fields.

The embodiments described above are used to further explain the best mode known to the present invention and enable those skilled in the art to utilize the present invention. Variations of the various variations resulting from the particular application or use of the invention are set forth herein or in other embodiments. Therefore, the description is not intended to limit the invention to the forms disclosed.

12‧‧‧ Controller

L1‧‧‧Inductance components

L2‧‧‧Inductive components

C1‧‧‧Capacitive components

R1‧‧‧Resistors

M1‧‧‧ MOSFET

D1‧‧‧ diode

Claims (19)

A circuit for providing a connection between a first node of a first voltage and a second node of a second voltage, comprising: a first inductive component having the first a first terminal connected to the node, a first switching element, the first switching element being between a second terminal and the second node of the first inductive component, a second inductive component, and the second inductive component Having a first terminal configured to receive current from the second terminal of the first inductive component, and having a second terminal coupled to a third node, and a second switch An element, the second switching element is coupled between the first terminal of the second inductive element and the second node, and when the first switching element is turned on and the second switching element is turned off, the first switching element is Configuring to provide a first path for a current flow between the first node and the second node, and when the second switching element is open and the first switching element is off, the second switching element is configured Provided for the first node with A second one of the current flow path between the second node. The circuit of claim 1, further comprising a capacitive element coupled between the second terminal of the first inductive component and the first terminal of the second inductive component. The circuit of claim 2, further comprising a controller configured to control a duty cycle of the first switching element. The circuit of claim 1, wherein one of the first switching element and the second switching element comprises a transistor, and the other switching element comprises a diode, when the first switching element is turned off, The diode is configured to conduct current. The circuit of claim 1, wherein the first switching element comprises a first transistor and the second switching element comprises a second transistor. The circuit of claim 1, wherein the first inductive component and the second inductive component are magnetically disengaged. The circuit of claim 1, wherein the first inductive component is magnetically coupled to the second inductive component. The circuit of claim 1 further comprising a current sense resistor configured to determine a sum of current flows through the first inductive component and the second inductive component. The circuit of claim 3, wherein the controller is configured to control a switch of the first switching element to provide a voltage of the second node that is adjusted relative to a voltage of the first node. The circuit of claim 3, wherein the controller is configured to control a switch of the first switching element to provide a desired level of a voltage of the second node, the desired level of the voltage of the second node Below a voltage of the first node. The circuit of claim 3, further comprising a feedback loop for providing a value indicative of the voltage of the second node to a controller. The circuit of claim 3, further comprising a feedback loop for providing a value representative of a voltage of the second node to a controller, and a current sensing resistor for the current sensing resistor The controller is enabled to determine the current of the second node. The circuit of claim 3, wherein the controller is configured to operate in a fixed frequency mode. The circuit of claim 3, wherein the controller is configured to operate in a hysteresis mode. The circuit of claim 1 is configured as a heat exchange circuit for attaching a load to the second node to receive a voltage from the first node. The circuit of claim 1 is configured as an overvoltage protection circuit for protecting a load coupled to the second node from voltage spikes of the first node. A method for providing a connection between a first node of a first voltage and a second node of a second voltage, the method comprising the steps of: between the first node and a third node Coupling a first inductive component and a second inductive component, a first terminal of the first inductive component is coupled to the first node, and a first terminal of the second inductive component is configured to receive from the first a current of a second terminal of the inductive component, and a second terminal of the second inductive component coupled to the third node, coupling a first switching component to the second node and the first inductive component Between the first terminal, a second switching element is coupled between the second node and the first terminal of the second inductive component, and the first switching component and the second switching component are switched to provide The first and second current flows of the first switching element and the second switching element are exchanged. The method of claim 17, wherein a capacitive element is coupled between the second terminal of the first inductive component and the first terminal of the second inductive component. The method of claim 17, wherein the second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.